Multi-mode defect nondestructive detection device and detection method for metal rolling body

Abstract

The invention discloses a multi-mode defect nondestructive testing device for a metal rolling body, which comprises a V-shaped rolling clamp, a signal detection and synchronous triggering system, a data acquisition unit and a processing unit, and is characterized in that the metal rolling body is arranged on the V-shaped rolling clamp and is in rolling fit with the clamp; the signal detection and synchronous triggering system is connected with a first detection light path, a second detection light path and a third detection light path which are used for detecting the metal rolling body, the first detection light path and the second detection light path are respectively connected with the processing unit, and the third detection light path is connected with the data collector. And the data acquisition unit is connected with the signal detection and synchronous triggering system and the processing unit respectively. According to the invention, multi-modal information can be fused to realize comprehensive detection of defects of the metal rolling body, and the method has the characteristics of high detection efficiency, high detection precision and strong adaptability.

Description

Technical Field

[0001] The present invention belongs to the field of nondestructive testing technology, and specifically relates to a nondestructive testing device and a testing method for multi-modal defects of a metal rolling body. Background Art

[0002] Under the background of the rapid development of modern industry and science and technology, the field of nondestructive testing has been actively exploring various advanced testing technologies to meet the increasingly complex testing needs. Most of the existing nondestructive testing technologies use single-mode signals to diagnose defects, but due to the limitations of technical principles, these technologies can basically only detect a certain type of defects in a certain part of the material. For example, magnetic particle testing can basically only detect defects on the surface of the material; ultrasonic testing is not effective for shallow surface defects and is often used for the detection of internal defect information, etc. Moreover, many detection methods can only obtain one-dimensional signals, and can often only qualitatively judge whether there are defects and whether they are serious. The information obtained is less, which is not conducive to the accurate assessment of defect conditions and the formulation of maintenance strategies. In addition, traditional nondestructive testing technology usually requires a comprehensive scan of the material to obtain the defect information of the material, and the detection efficiency is very low. Summary of the invention

[0003] The purpose of the present invention is to provide a nondestructive detection device and method for multimodal defects of metal rolling elements. The present invention can integrate multimodal information to achieve comprehensive detection of defects of metal rolling elements, and has the characteristics of high detection efficiency, high detection accuracy and strong adaptability.

[0004] The technical solution of the present invention is as follows: a multi-modal defect nondestructive detection device for a metal rolling body, which is used for detecting a metal rolling body; it comprises a V-shaped rolling fixture, a signal detection and synchronous triggering system, a data collector and a processing unit, wherein the metal rolling body is arranged on the V-shaped rolling fixture and rollingly cooperates with the fixture; the signal detection and synchronous triggering system is connected with a first detection optical path, a second detection optical path and a third detection optical path for detecting the metal rolling body, the first detection optical path and the second detection optical path are respectively connected with the processing unit, the third detection optical path is connected with the data collector, and the data collector is respectively connected with the signal detection and synchronous triggering system and the processing unit;

[0005] The first detection optical path includes a 2.5D stripe light source and a linear array camera arranged above the metal rolling body, the 2.5D stripe light source is used to project regular grating stripes onto the cylindrical surface of the metal rolling body, and the linear array camera is used to collect optical signals on the cylindrical surface of the metal rolling body;

[0006] The second detection optical path includes a group of annular light sources arranged on both sides of the end face of the metal rolling body, and an area array camera is arranged outside the annular light source; the annular light source is used to provide uniform diffuse reflection illumination to the end surface of the metal rolling body cylinder, and the area array camera is used to collect optical signals from the end surface of the metal rolling body;

[0007] The third detection optical path includes an infrared pulse laser and an ultrasonic probe. An optical fiber coupler, an optical fiber and a laser galvanometer are arranged in sequence on the output optical path of the infrared pulse laser. The infrared pulse laser is used to generate a pulse laser for scanning the area to be tested of the metal rolling body. The pulse laser is coupled to the optical fiber through the optical fiber coupler and is uniformly irradiated onto the surface of the metal rolling body through the laser galvanometer. The ultrasonic probe is used to collect photoacoustic signals of the shallow surface layer of the metal rolling body and ultrasonic signals inside the metal rolling body.

[0008] In the aforementioned multimodal defect nondestructive detection device for metal rolling bodies, a stripe light source controller is connected between the first detection optical path and the signal detection and synchronization triggering system, and the stripe light source controller is connected to the 2.5D stripe light source; the linear array camera is connected to the processing unit; and the optical axis of the linear array camera and the 2.5D stripe light source is at 30°-45°.

[0009] In the aforementioned nondestructive detection device for multimodal defects of metal rolling bodies, an annular light source controller is connected between the second detection optical path and the signal detection and synchronous triggering system, and the annular light source controller is connected to the annular light source; and the area array camera is connected to the processing unit.

[0010] In the aforementioned nondestructive detection device for multimodal defects of metal rolling bodies, an infrared laser controller is connected between the third detection optical path and the signal detection and synchronization triggering system, and the infrared laser controller is connected to the infrared pulse laser; and the ultrasonic probe is connected to the data collector.

[0011] The detection method of the aforementioned multi-modal defect non-destructive detection device for metal rolling elements specifically comprises the following steps:

[0012] Step 1: Based on the first detection optical path and the second detection optical path, optical detection is performed on the surface of the metal rolling body to obtain optical signals of the cylindrical surface and the end surface of the metal rolling body, and defects of the cylindrical surface and the end surface of the metal rolling body are determined according to the obtained optical signals;

[0013] Step 2: Based on the third detection optical path, photoacoustic detection is performed on the shallow surface of the metal rolling element to obtain a photoacoustic signal of the shallow surface of the metal rolling element, and a defect of the shallow surface of the metal rolling element is determined according to the obtained photoacoustic signal;

[0014] Step 3: Based on the third detection optical path, ultrasonic detection is performed on the inside of the metal rolling element to obtain an ultrasonic signal inside the metal rolling element, and internal defects of the metal rolling element are determined based on the obtained ultrasonic signal;

[0015] Step 4: Based on the surface defects, shallow surface defects and internal defects of the metal rolling element, multi-modal signal fusion is performed to obtain fused defect information, and the defects are located based on the fused defect information.

[0016] In the detection method of the multimodal defect nondestructive detection device for metal rolling bodies, the acquisition process of the optical signal on the surface of the metal rolling body cylinder is that the linear array camera collects the optical signal reflected from the surface of the metal rolling body cylinder line by line, and the collected optical signal formula is:

[0017] I optical,line =∫ y I(x',y')dy;

[0018] Among them, I optical,line is the optical signal collected by the line array camera, x' and y' are the pixel coordinates collected by the line array camera, and x and y are the coordinates of the metal rolling body in the actual physical space; I(x', y') is determined by the surface reflectivity R(x, y) and the light source intensity I0, and the formula is as follows:

[0019] I(x',y')=I0R(x,y);

[0020] The process of determining the surface defects of the metal rolling element cylinder is to use the optical signal I optical,line Determine the surface texture and defect characteristics of metal rolling elements, and obtain the morphological characteristics of protrusions, cracks or scratches on the surface of metal rolling element cylinders through three-dimensional reconstruction;

[0021] The formula for the three-dimensional reconstruction is as follows:

[0022]

[0023] Where z(x,y) is the surface height distribution, d is the projection grating spacing, and I1, I2, I3, and I4 are the light intensity values ​​after fringe phase shift.

[0024] In the aforementioned detection method of the multi-modal defect non-destructive detection device for metal rolling elements, the process of acquiring the optical signal of the end surface of the metal rolling element is as follows:

[0025] Calculate the reflected light intensity I(x,y) on the end surface of the metal rolling element using the following formula:

[0026] I(x,y)=I0R(x,y)=I0cos n (θ);

[0027] Where I0 is the intensity of the light source, x and y are the coordinates of the metal rolling body in the actual physical space, R(x,y) is the reflectivity, θ is the angle between the normal line of the end surface of the metal rolling body and the direction of the annular light source, and n is the reflection distribution index;

[0028] Then the area array camera records the two-dimensional light intensity distribution of the reflected light intensity on the end surface of the metal rolling element to obtain the optical signal. The calculation formula is as follows:

[0029] I optica,lring =I (i,j) =∫ Δx ∫ Δy I(x,y)dxdy;

[0030] In the formula, I optical,ring is the optical signal collected by the area array camera, Δx is the spatial resolution, Δy is the sampling interval, and the light intensity corresponding to the pixel (i, j) is determined by the reflection characteristics of the end surface of the metal rolling element;

[0031] The process of determining the surface defects of the metal rolling element end is to use the discontinuity of light intensity distribution to detect surface pits, scratches or coating shedding, and analyze the image gradient information after optical distortion correction to extract subtle defects.

[0032] In the aforementioned detection method of the multi-modal defect non-destructive detection device for metal rolling elements, the process of acquiring the photoacoustic signal of the shallow surface layer of the metal rolling element is as follows:

[0033] The energy absorbed by the metal rolling element is converted into heat energy, which causes transient expansion. The sound pressure caused by the thermal expansion satisfies the sound wave equation:

[0034]

[0035] In the formula, p represents the sound pressure, v represents the speed of sound wave propagation, and t represents time;

[0036] The time harmonic solution of the sound pressure is:

[0037] p(x,t)=P0exp[j(ωt-kx)];

[0038] Where p(x,t) represents the time harmonic of the sound pressure, P0 represents the sound pressure amplitude, and k is the wave number. The calculation formula is:

[0039]

[0040] The calculation formula of P0 is:

[0041] P0=P acoustic =βA e ;

[0042] Where P acousticis the sound pressure amplitude of the photoacoustic signal, β is the conversion coefficient of the photoacoustic effect, which depends on the thermal expansion coefficient, thermoelastic properties and sound wave propagation efficiency of the material, A e is the energy absorbed by the metal rolling element, and the calculation formula is as follows:

[0043] A e =I0f(x,y,z)g(t)α;

[0044] Where f(x,y,z) is the spatial distribution of laser energy, g(t) is the time distribution function, usually an exponential pulse, and α is the material absorption coefficient;

[0045] Then, the photoacoustic signal is obtained through the sound pressure formula generated by the photoacoustic effect. The formula is as follows:

[0046] I photoacoustic =P acoustic ;

[0047] In the formula, I photocoustic It is a photoacoustic signal;

[0048] The process of determining the shallow surface defects of the metal rolling element is to reveal the type and size of the defect through the frequency characteristics of the photoacoustic signal, and then calculate the defect depth through the ultrasonic delay. The formula is as follows:

[0049]

[0050] Where d is the defect depth, v is the propagation velocity of the sound wave, and Δt is the time difference of signal propagation.

[0051] In the aforementioned detection method of the multi-modal defect non-destructive detection device for metal rolling elements, the process of acquiring the ultrasonic signal inside the metal rolling element is as follows:

[0052] Ultrasonic waves satisfy the wave equation:

[0053]

[0054] In the formula, u is displacement, v represents propagation velocity, and t represents time;

[0055] The ultrasonic signal is obtained through the ultrasonic probe echo signal:

[0056] I ultrasound =A echo ;

[0057] In the formula, I ultrasound is the ultrasonic signal, A echo is the amplitude of the ultrasound probe echo signal;

[0058] The calculation formula of the echo signal V(t) received by the ultrasonic probe is as follows:

[0059] V(t)=G∫ 孔径 p(x,y,t)dxdy;

[0060] Where G is the sound wave transfer function, which represents the loss and scattering effect of sound waves propagating inside the metal rolling element, p(x, y, t) is the distribution of sound pressure, and x and y represent the spatial coordinates of the metal rolling element;

[0061] The amplitude A of the ultrasonic probe echo signal echo Corresponding to the maximum value of V(t);

[0062] The process of determining the internal defects of the metal rolling element is to use the amplitude A of the echo signal of the ultrasonic probe echo Determine the characteristics of the defect and calculate the defect depth by ultrasonic delay. The formula is as follows:

[0063]

[0064] In the aforementioned detection method of the multimodal defect nondestructive detection device for metal rolling elements, in step 4, the multimodal signal fusion is achieved by weighted summation:

[0065] I fused =w1I optical,line +w2I optical,ring +w3I photocoustic +w4I ultrasound ;

[0066] Among them, I fused is a multimodal fusion signal, and the weights w1, w2, w3, and w4 are determined by signal-to-noise ratio optimization. The calculation formula is as follows:

[0067]

[0068] In the formula, w i represents the weight of the i-th signal, SNR i represents the signal-to-noise ratio of the ith signal, P signal,i Represents the signal power, P noise,i represents the noise power;

[0069] The calculation formula for defect location is as follows:

[0070]

[0071] Where d is the defect depth, v is the propagation velocity of the sound wave, and Δt is the time difference of signal propagation.

[0072] Compared with the prior art, the present invention has the following beneficial effects:

[0073] The present invention uses 2.5D stripe light and linear array camera, annular light and area array camera to collect high-resolution optical signals respectively, and combines infrared pulse laser and ultrasonic probe to obtain photoacoustic signal and ultrasonic signal, which can perform all-round multimodal detection on metal rolling elements with multi-type and multi-size defects, including surface defects (such as scratches, pits) and internal defects (such as cracks, pores), and at the same time, through the use of high-precision data synchronous acquisition and fusion processing technology, the comprehensive extraction of defect features is realized. The present invention performs multimodal fusion processing on the collected data, and the system can accurately realize the positioning, size measurement and depth information extraction of defects. Further combined with the spectrum analysis of photoacoustic and acoustic wave signals, the characteristic frequency information of defects is extracted to identify different types of defects. The present invention solves the problem that traditional detection technology is easily affected by the surface characteristics of metal rolling elements (such as high reflectivity and roughness) in a single detection mode by combining optical path optimization with multimodal detection technology, overcomes the shortcomings of traditional detection range limitation and inability to detect surface and deep defects at the same time, and is suitable for more complex detection scenarios. In addition, the present invention also effectively improves the accuracy and robustness of defect recognition by combining multimodal information such as surface stripe images, polarization characteristic images, and 3D depth maps, solving the problem that traditional single information sources are difficult to detect complex defects. Through the integration of anti-reflective interference, environmental robustness enhancement, and surface and deep detection capabilities, the present invention significantly expands the scope of application, and is suitable for defect recognition from highly reflective metal rolling body surface detection to complex structural components and multi-layer materials. Its wide adaptability enables the system to meet the diverse detection needs in modern industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Figure 1 It is a schematic diagram of the detection device of the present invention;

[0075] Figure 2 is a schematic diagram of the thermoelastic mechanism of the present invention;

[0076] Figure 3 A schematic diagram of the thermoelastic mechanism of the present invention for generating ultrasound;

[0077] Figure 4 A diagram of the process of generating ultrasound for the thermoelastic mechanism of the present invention;

[0078] Figure 5 is a schematic diagram of optical imaging of the present invention;

[0079] Figure 6 A schematic diagram of the directivity of ultrasound of the present invention;

[0080] Figure 7 It is a schematic diagram of ultrasonic reflection and transmission of the present invention. DETAILED DESCRIPTION

[0081] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but they are not intended to limit the present invention.

[0082] Embodiment 1: A multi-modal defect nondestructive detection device for a metal rolling element, such as Figure 1 As shown, it is used to detect metal rolling bodies; it includes a V-shaped rolling fixture, a signal detection and synchronous triggering system, a data collector and a processing unit, the metal rolling body is arranged on the V-shaped rolling fixture and rollingly cooperates with the fixture; the signal detection and synchronous triggering system is connected with a first detection optical path, a second detection optical path and a third detection optical path for detecting the metal rolling body, the first detection optical path and the second detection optical path are respectively connected to the processing unit, the third detection optical path is connected to the data collector, and the data collector is respectively connected to the signal detection and synchronous triggering system and the processing unit;

[0083] The first detection optical path includes a 2.5D stripe light source and a linear array camera arranged above the metal rolling body. The 2.5D stripe light source generates high-contrast stripes through structured grating projection, which is used to project regular grating stripes onto the surface of the metal rolling body cylinder. The 2.5D stripe light source is projected vertically onto the surface of the metal rolling cylinder, and the metal rolling body is supported by the V-shaped rolling clamps on both sides, so that the metal rolling body can complete full surface coverage during rotation. The linear array camera uses a linear array CCD (charge-coupled device) sensor, which is suitable for imaging high-speed or continuously moving objects. The linear array camera uses a single row of pixels to gradually scan the surface of the metal rolling cylinder to collect optical signals from the surface of the metal rolling cylinder. The optical signal is a signal that uses optical instruments (linear array cameras and area array cameras) to detect the reflected, scattered or transmitted light information on the surface of the metal rolling material, and is used to identify surface defects of the metal rolling body, such as cracks, scratches, and corrosion. A stripe light source controller is connected between the first detection optical path and the signal detection and synchronization triggering system, and the stripe light source controller is connected to the 2.5D stripe light source; the line array camera is connected to the processing unit; the optical axis of the line array camera and the 2.5D stripe light source is 30°-45° to avoid the mirror reflection area and ensure high-contrast signal acquisition. A narrowband filter is also provided in the first detection optical path to match the wavelength of the stripe light to avoid ambient light interference, and an infrared cutoff filter is added to suppress blur and distortion caused by infrared light interference.

[0084] The second detection optical path includes a group of annular light sources arranged on both sides of the end face of the metal rolling body. The annular light sources are arranged around the optical axis of the area array camera, and the optical axis is perpendicular to the end face to provide all-round uniform illumination. The annular light source is used to provide uniform diffuse reflection illumination to the end surface of the metal rolling body cylinder, avoiding shadow interference and enhancing the visibility of end face defects (such as scratches and pits). An area array camera is arranged outside the annular light source. The area array camera is an imaging device that uses an area array sensor (usually a CCD or CMOS sensor) and can collect images in a two-dimensional (X and Y directions) area at one time, which is used to collect optical signals on the end surface of the metal rolling body. The optical axis of the area array camera is consistent with the end face normal to ensure distortion-free light intensity distribution. A ring light source controller is connected between the second detection optical path and the signal detection and synchronization trigger system, and the ring light source controller is connected to the annular light source; the area array camera is connected to the processing unit. In order to meet the high-precision requirements, a high-pass filter is added to the second detection optical path to shield the interference of lower-frequency background light, and an infrared cutoff filter is added to suppress infrared light interference.

[0085] The third detection optical path includes an infrared pulse laser and an ultrasonic probe. The output optical path of the infrared pulse laser is provided with a fiber coupler, an optical fiber and a laser galvanometer in sequence. The infrared pulse laser is used to generate a pulse laser for scanning the area to be tested of the metal rolling body. The infrared pulse laser uses a nanosecond pulse laser to excite sound waves through the thermoelastic effect on the surface of the metal rolling body. The wavelength and pulse width of the laser are optimized to match the energy absorption peak of the metal rolling body surface and improve the excitation efficiency of the photoacoustic effect. The laser power density is controlled at 106106W / cm 2In the following, ablation and surface damage are avoided to ensure the integrity of the material. The ultrasonic probe is used to collect the photoacoustic signal of the shallow surface of the metal rolling element and the ultrasonic signal inside the metal rolling element. The ultrasonic probe is provided with a photoacoustic sensor for capturing the photoacoustic signal. The photoacoustic signal is to use pulsed laser to irradiate the surface of the metal rolling element material, generate local thermal expansion and excite sound waves, and analyze the shallow surface defects by detecting the characteristics of these sound waves. The sound waves generated by the photoacoustic effect propagate through the metal rolling element in the form of surface waves and body waves, and the signal is captured by the photoacoustic sensor with wide-band response. The ultrasonic signal is to emit high-frequency sound waves through the ultrasonic probe, and the sound waves propagate and reflect in the metal rolling element. According to the characteristics of the reflected wave, the internal defects of the metal rolling element, such as holes and cracks, are detected. The third detection optical path excites the ultrasonic signal through the laser, uses the reflected wave to collect, captures the reflected signal of the ultrasonic wave on the defective surface, extracts its waveform morphology changes, and determines the defect shape and characteristics. After the ultrasonic echo signal is collected and preprocessed in real time, the propagation time, amplitude and frequency changes are extracted using an improved delay estimation algorithm. An infrared laser controller is connected between the third detection optical path and the signal detection and synchronous triggering system, and the infrared laser controller is connected to an infrared pulse laser; the ultrasonic probe is connected to a data collector. In order to improve the detection sensitivity, multi-stage low-noise amplification and adaptive filtering technology are used in the signal path of the third detection optical path to effectively eliminate background noise interference. Combined with digital signal processing algorithms, time domain and frequency domain feature extraction is performed to identify sound pressure amplitude, propagation wave velocity and amplitude changes, and accurately characterize superficial defects (such as crack depth, inclination angle and other parameters).

[0086] The core design of the signal detection and synchronous triggering system is based on the gradual collection of three signals (optical signal, photoacoustic signal, and ultrasonic signal) after the metal rolling body rotates one circle, and the use of a unified time reference to achieve time axis alignment and multimodal fusion of the data.

[0087] The architecture of the signal detection and synchronization trigger system includes a time base trigger and a registration and fusion module. The time base trigger provides time control for the acquisition of each modal signal to ensure the alignment of the time axis between different signals. The registration and fusion module calculates the time deviation of each modal signal acquisition based on the rolling body speed and position feedback to complete the signal alignment. Then, the surface information of the optical signal, the shallow characteristics of the photoacoustic signal, and the depth data of the ultrasonic signal are combined to construct a three-dimensional defect map.

[0088] The signal detection and synchronous triggering system uses a unified time reference trigger to ensure that the acquisition of optical signals, photoacoustic signals and ultrasonic signals is completed within the set time window. After each signal acquisition, the metal rolling body returns to the initial position to collect the next modal signal. After the three signals are acquired, the registration and fusion module maps the data to the same time reference system through the time axis alignment algorithm to avoid the accumulation of multi-modal signal errors, and combines the time and space characteristics for multi-modal fusion processing to generate a complete defect model from the surface to the deep layer.

[0089] Advantages of signal detection and synchronous trigger system:

[0090] 1. It can avoid possible signal interference during simultaneous acquisition;

[0091] 2. Use a unified time base to ensure the time consistency of data of different modalities;

[0092] 3. Collect signals in stages according to the mode to improve acquisition efficiency and reduce system complexity.

[0093] Principle of optical nondestructive testing: The optical imaging system (line array camera and area array camera) collects the light signal reflected or emitted by the surface of the object and converts the observed object into a visual image (such as Figure 5 As shown in the figure, by using high pixels and advanced photosensitive elements, optical imaging can generate high-resolution, high-contrast defect images, and accurately detect the location, size and type of defects by analyzing information such as pixel distribution, brightness and color.

[0094] Photoacoustic nondestructive testing principle: In the visible light range, when the laser irradiates the metal surface, it will stimulate ultrasonic signals. 7 W / cm 2 When the laser is heated, the ultrasonic wave is mainly generated by the thermoelastic mechanism. Under this mechanism, the amplitude of the photoacoustic longitudinal wave, transverse wave and surface wave will increase with the increase of laser energy density, and the relationship between the acoustic wave amplitude and the laser energy density is approximately linear. The schematic diagram of the thermoelastic mechanism is shown in Figure 2 shown.

[0095] In photoacoustic nondestructive testing, the photoacoustic effect is usually generated under the thermoelastic mechanism (laser energy density is less than 10 7 W / cm 2 ). When the pulsed laser beam is irradiated on the surface of the material, part of the laser energy A e It is absorbed by the material, accumulated in the local area and converted into heat energy. The change of local temperature T causes the volume of the material to expand and contract periodically, thus forming an elastic stress field, that is, an ultrasonic field. This process is the process of generating ultrasonic waves through the thermoelastic mechanism, and its schematic diagram is shown in the figure. Figure 3 and Figure 4 shown.

[0096] Principle of ultrasonic nondestructive testing: Ultrasonic waves are mechanical waves with a frequency higher than 20kHz, usually generated and received by piezoelectric materials through the mutual conversion of electrical energy and mechanical energy. When receiving electrical energy, piezoelectric materials convert it into mechanical vibration to generate ultrasonic waves, and at the same time, they can convert the received mechanical vibration into electrical signals to collect ultrasonic data. Ultrasonic waves have good directivity and strong metal penetration ability. Their directional distribution is as follows: Figure 6 As shown, the central main lobe is the main propagation direction in which the energy is concentrated, and the side lobes on both sides are the diffuse parts with smaller energy.

[0097] Ultrasonic nondestructive testing detects defects inside materials through the reflection, scattering and transmission of ultrasonic waves in materials. When ultrasonic waves propagate to the interface where two acoustic impedances (acoustic impedance Z is determined by density ρ and sound speed v) in the material have significant differences, due to the mismatch of acoustic impedances, part of the ultrasonic waves will be reflected at the interface, and the other part will be transmitted into another material, such as Figure 7 shown.

[0098] The third detection optical path can use ultrasonic imaging technology to construct image information containing internal defects by accurately measuring the characteristics of reflected waves and scattered waves. The ultrasonic signal collected by the ultrasonic probe carries information about the internal structure and defects of the material. After data processing, an intuitive internal defect image can be generated, thereby achieving quantitative analysis of the defect location, size and properties.

[0099] Embodiment 2: Based on the multi-modal defect non-destructive detection device in Embodiment 1, this embodiment provides a multi-modal defect non-destructive detection method for a metal rolling element, which specifically includes the following steps:

[0100] Step 1: Based on the first detection optical path and the second detection optical path, optical detection is performed on the surface of the metal rolling body to obtain optical signals of the cylindrical surface and the end surface of the metal rolling body, and defects of the cylindrical surface and the end surface of the metal rolling body are determined according to the obtained optical signals;

[0101] In this embodiment, the process of acquiring the optical signal on the surface of the metal rolling body cylinder is that the linear array camera collects the optical signal reflected from the surface of the metal rolling body cylinder line by line, and the formula of the collected optical signal is:

[0102] I optical,line =∫ y I(x',y')dy;

[0103] Among them, I optical,line is the optical signal collected by the linear array camera, x' and y' are the pixel coordinates collected by the linear array camera, and x and y are the coordinates of the metal rolling body in the actual physical space;

[0104] Specifically, I(x',y') is determined by the surface reflectivity R(x,y) and the light source intensity I0, and the formula is as follows:

[0105] I(x',y')=I0R(x,y);

[0106] Furthermore, the process of determining the surface defects of the metal rolling element cylinder is to use the optical signal I optical,line Determine the surface texture and defect characteristics of metal rolling elements, and obtain the morphological characteristics of protrusions, cracks or scratches on the surface of metal rolling element cylinders through three-dimensional reconstruction;

[0107] The formula for the three-dimensional reconstruction is as follows:

[0108]

[0109] Where z(x,y) is the surface height distribution, d is the projection grating spacing, and I1, I2, I3, and I4 are the light intensity values ​​after fringe phase shift.

[0110] In this embodiment, the process of acquiring the optical signal of the end surface of the metal rolling element is as follows:

[0111] Calculate the reflected light intensity I(x,y) on the end surface of the metal rolling element using the following formula:

[0112] I(x,y)=I0R(x,y)=I0cos n (θ);

[0113] Where I0 is the intensity of the light source, x and y are the coordinates of the metal rolling body in the actual physical space, R(x,y) is the reflectivity, θ is the angle between the normal line of the end surface of the metal rolling body and the direction of the annular light source, and n is the reflection distribution index;

[0114] Then, the area array camera records the two-dimensional light intensity distribution of the reflected light intensity on the end surface of the metal rolling element to obtain the optical signal. The calculation formula is as follows:

[0115] I optica,lring =I (i,j) =∫ Δx ∫ Δy I(x,y)dxdy;

[0116] In the formula, I optical,ring is the optical signal collected by the area array camera, Δx is the spatial resolution, Δy is the sampling interval, and the light intensity corresponding to the pixel (i, j) is determined by the reflection characteristics of the end surface of the metal rolling element;

[0117] Furthermore, the process of determining the surface defects of the end of the metal rolling element is to use the discontinuity of the light intensity distribution to detect surface pits, scratches or coating peeling, and analyze the image gradient information after optical distortion correction to extract subtle defects.

[0118] Step 2: Based on the third detection optical path, photoacoustic detection is performed on the shallow surface of the metal rolling element to obtain a photoacoustic signal of the shallow surface of the metal rolling element, and a defect of the shallow surface of the metal rolling element is determined according to the obtained photoacoustic signal;

[0119] In this embodiment, the process of acquiring the photoacoustic signal of the shallow surface layer of the metal rolling element is as follows:

[0120] The energy absorbed by the metal rolling element is converted into heat energy, which causes transient expansion. The sound pressure caused by the thermal expansion satisfies the sound wave equation:

[0121]

[0122] In the formula, p represents the sound pressure, which represents the intensity of the sound wave; v represents the speed of sound wave propagation, which depends on the material elasticity and density of the metal rolling element; t represents time, which is usually related to the time delay of the ultrasonic wave propagation path;

[0123] The time harmonic solution of the sound pressure is:

[0124] p(x,t)=P0exp[j(ωt-kx)];

[0125] Where p(x,t) represents the time harmonic of the sound pressure, P0 represents the sound pressure amplitude, which depends on the conversion efficiency of the photoacoustic effect, and k is the wave number. The calculation formula is:

[0126]

[0127] The calculation formula of P0 is:

[0128] P0=P acoustic =βA e ;

[0129] Where P acoustic is the sound pressure amplitude of the photoacoustic signal, β is the conversion coefficient of the photoacoustic effect, which depends on the thermal expansion coefficient, thermoelastic properties and sound wave propagation efficiency of the material, A e The energy absorbed by the metal rolling element can reflect the depth and size of the material defect. The calculation formula is as follows:

[0130] A e =I0f(x,y,z)g(t)α;

[0131] Where f(x,y,z) is the spatial distribution of laser energy, g(t) is the time distribution function, usually an exponential pulse, and α is the material absorption coefficient;

[0132] Then, the photoacoustic signal is obtained through the sound pressure formula generated by the photoacoustic effect. The formula is as follows:

[0133] I photoacoustic =Pacoustic ;

[0134] In the formula, I photocoustic It is a photoacoustic signal;

[0135] Furthermore, the process of determining the shallow surface defects of the metal rolling element is to reveal the type and size of the defects through the frequency characteristics of the photoacoustic signal, and then calculate the defect depth through the ultrasonic delay, and the formula is as follows:

[0136]

[0137] Step 3: Based on the third detection optical path, ultrasonic detection is performed on the inside of the metal rolling element to obtain an ultrasonic signal inside the metal rolling element, and internal defects of the metal rolling element are determined based on the obtained ultrasonic signal;

[0138] In this embodiment, the process of acquiring the ultrasonic signal inside the metal rolling element is as follows:

[0139] Ultrasonic waves satisfy the wave equation:

[0140]

[0141] In the formula, u is displacement, v represents propagation velocity, and t represents time;

[0142] Specifically, the ultrasonic signal is obtained through the ultrasonic probe echo signal:

[0143] I ultrasound =A echo ;

[0144] In the formula, I ultrasound is the ultrasonic signal, A echo is the amplitude of the ultrasound probe echo signal;

[0145] The calculation formula of the echo signal V(t) received by the ultrasonic probe is as follows:

[0146] V(t)=G∫ 孔径 p(x,y,t)dxdy;

[0147] Where G is the sound wave transfer function, which represents the loss and scattering effect of sound waves propagating inside the metal rolling element; p(x, y, t) is the distribution of sound pressure, which is used to describe the propagation and time-varying characteristics of sound waves in space, and x and y represent the spatial coordinates of the metal rolling element;

[0148] The acoustic wave transfer function G is obtained by experimental calibration (using standard samples, measuring the acoustic wave transfer function G under different environmental conditions, and constructing a calibration curve) and simulation (using the finite element method to simulate different combinations of defects and material properties and predict the change law of the acoustic wave transfer function G), and the formula is expressed as follows:

[0149] G(f,r,θ)=A(f)·e-α(f)r·P(θ);

[0150] In the formula, f is the sound wave frequency, which indicates the propagation frequency of the sound wave; r is the propagation distance; θ is the propagation direction; A(f) is the initial intensity of the sound wave related to the frequency; α(f) is the attenuation coefficient, which describes the attenuation speed of the sound wave in the metal rolling element with the propagation distance. The attenuation coefficient α(f) is related to the density, elastic modulus and internal friction characteristics of the metal rolling element material; P(θ) is the angular distribution function, which indicates the directional change of the sound wave due to the propagation direction or surface scattering.

[0151] The amplitude A of the ultrasonic probe echo signal echo Corresponding to the maximum value of V(t);

[0152] Furthermore, the process of determining the internal defects of the metal rolling element is to measure the amplitude A of the echo signal of the ultrasonic probe. echo Determine the characteristics of the defect and calculate the defect depth by ultrasonic delay. The formula is as follows:

[0153]

[0154] Where d is the defect depth, that is, the depth of the signal reflection (or scattering) position; v is the propagation speed of the sound wave; Δt is the time difference of signal propagation, usually the time between the transmitted signal and the received reflected signal.

[0155] Step 4: Based on the surface defects, shallow surface defects and internal defects of the metal rolling element, multi-modal signal fusion is performed to obtain fused defect information, and the defects are located based on the fused defect information.

[0156] In this embodiment, multimodal signal fusion is a technology that jointly processes and analyzes signal data from different detection methods (such as optical, photoacoustic, and ultrasonic), which can improve the comprehensiveness and accuracy of detection. This method preprocesses the images obtained by optical, photoacoustic, and ultrasonic signals, including noise reduction, enhancement, and edge detection, and uses wavelet transform for image fusion to retain the spatial resolution of optical images and the depth information of photoacoustic and ultrasonic signals. Multimodal signal fusion integrates data of different modes through time synchronization and spatial alignment processing to achieve deep positioning and accurate characterization of metal defects. By constructing a three-dimensional defect model of multimodal signals, complete reconstruction of defects from the surface to the inside is achieved.

[0157] The multimodal signal fusion is achieved by weighted summation:

[0158] I fused =w1I optical,line +w2I optical,ring +w3I photocoustic +w4Iultrasound ;

[0159] Among them, I fused is a multimodal fusion signal, and the weights w1, w2, w3, and w4 are determined by signal-to-noise ratio optimization. The calculation formula is as follows:

[0160]

[0161] In the formula, w i represents the weight of the i-th signal, SNR i represents the signal-to-noise ratio of the ith signal, P signal,i Represents the signal power, P noise,i represents the noise power;

[0162] Furthermore, according to the fused defect information, the defect location calculation formula is as follows:

[0163]

[0164] Where d is the defect depth, v is the propagation velocity of the sound wave, and Δt is the time difference of signal propagation.

[0165] The present invention uses a multimodal fusion algorithm based on spatiotemporal characteristics to jointly analyze the waveform characteristics of photoacoustics and ultrasound: accurately locate the surface crack features (such as tilt angle and length) obtained by the photoacoustic signal, and use the penetration depth data of the ultrasonic signal to reconstruct the complete path of the crack extending from the surface to the inside. In the data fusion process, combined with the deep learning feature extraction network and the integrated wave signal, a three-dimensional spatial model of the defect from the surface to the depth is constructed, which significantly improves the accuracy and resolution of defect detection.

[0166] The present invention can perform all-round multimodal detection on metal rolling elements containing defects of multiple types and sizes, including surface defects (such as scratches and pits) and internal defects (such as cracks and pores). It uses stripe light and linear array cameras, annular light and area array cameras to collect high-resolution optical signals respectively, combines laser pulses and ultrasonic probes to obtain photoacoustic and acoustic wave signals, performs multimodal joint detection on samples, and uses high-precision data synchronous acquisition and fusion processing technology to achieve comprehensive extraction of defect features. The present invention performs multimodal fusion processing on the collected data, and the system can accurately locate the defects, measure the size and extract the depth information. It further combines the spectrum analysis of photoacoustic and acoustic wave signals to extract the characteristic frequency information of the defects, thereby identifying different types of defects.

[0167] The present invention solves the problem that traditional detection technology is easily affected by the surface characteristics of metal rolling elements (such as high reflectivity and roughness) in a single detection mode by combining optical path optimization and multimodal detection technology, overcomes the shortcomings of traditional detection range limitations and the inability to detect surface and deep defects at the same time, and is suitable for more complex detection scenarios. The present invention also effectively improves the accuracy and robustness of defect recognition by combining multimodal information such as surface stripe images, polarization characteristic images, 3D depth maps, and using information fusion algorithms or neural network models, solving the problem that traditional single information sources are difficult to detect complex defects. The present invention significantly expands the scope of application through the integration of anti-reflective interference, environmental robustness enhancement, and surface and deep detection capabilities. It is suitable for defect recognition from highly reflective metal rolling surface detection to complex structural components and multi-layer materials. Its wide adaptability enables the system to meet the diverse detection needs in modern industry.

[0168] Experimental results show that this technology exhibits excellent performance in defect detection:

[0169] 1. Detection accuracy: The detection accuracy of defect position, size and depth reaches micron level.

[0170] 2. Accuracy verification: Through comparative analysis with theoretical models and standard samples, the high accuracy and stability of the detection system in defect measurement are verified.

[0171] 3. Defect classification: The frequency response characteristics of photoacoustic and acoustic signals can be used to accurately distinguish between cracks, pores, corrosion and other defect types.

[0172] The experimental results fully prove that this technology can achieve high-precision detection and classification of multiple types of defects and has broad engineering application prospects. At the same time, the system's innovation in multimodal data fusion and defect identification technology provides important support for the quality inspection of complex structural materials.

[0173] In summary, the present invention can integrate multi-modal information to achieve comprehensive detection of metal rolling element defects, and has the characteristics of high detection efficiency, high detection accuracy and strong adaptability.

Claims

1. A multi-modal defect non-destructive detection device for metal rolling elements, used for detecting metal rolling elements; characterized in that: It includes a V-shaped rolling fixture, a signal detection and synchronous triggering system, a data collector and a processing unit, wherein the metal rolling body is arranged on the V-shaped rolling fixture and cooperates with the fixture in rolling; the signal detection and synchronous triggering system is connected with a first detection optical path, a second detection optical path and a third detection optical path for detecting the metal rolling body, the first detection optical path and the second detection optical path are respectively connected to the processing unit, the third detection optical path is connected to the data collector, and the data collector is respectively connected to the signal detection and synchronous triggering system and the processing unit; The first detection optical path includes a 2.5D stripe light source and a linear array camera arranged above the metal rolling body, the 2.5D stripe light source is used to project regular grating stripes onto the cylindrical surface of the metal rolling body, and the linear array camera is used to collect optical signals on the cylindrical surface of the metal rolling body; The second detection optical path includes a group of annular light sources arranged on both sides of the end face of the metal rolling body, and an area array camera is arranged outside the annular light source; the annular light source is used to provide uniform diffuse reflection illumination to the end surface of the metal rolling body cylinder, and the area array camera is used to collect optical signals from the end surface of the metal rolling body; The third detection optical path includes an infrared pulse laser and an ultrasonic probe. An optical fiber coupler, an optical fiber and a laser galvanometer are arranged in sequence on the output optical path of the infrared pulse laser. The infrared pulse laser is used to generate a pulse laser for scanning the area to be tested of the metal rolling body. The pulse laser is coupled to the optical fiber through the optical fiber coupler and is uniformly irradiated onto the surface of the metal rolling body through the laser galvanometer. The ultrasonic probe is used to collect photoacoustic signals of the shallow surface layer of the metal rolling body and ultrasonic signals inside the metal rolling body.

2. The multi-modal defect nondestructive testing device for metal rolling elements according to claim 1, characterized in that: A stripe light source controller is connected between the first detection optical path and the signal detection and synchronization trigger system, and the stripe light source controller is connected to the 2.5D stripe light source; the line array camera is connected to the processing unit; the optical axis of the line array camera and the 2.5D stripe light source is 30°-45°.

3. The multi-modal defect nondestructive testing device for metal rolling elements according to claim 1, characterized in that: An annular light source controller is connected between the second detection optical path and the signal detection and synchronization triggering system, and the annular light source controller is connected to the annular light source; and the area array camera is connected to the processing unit.

4. The multi-modal defect nondestructive testing device for metal rolling elements according to claim 1, characterized in that: An infrared laser controller is connected between the third detection optical path and the signal detection and synchronization triggering system, and the infrared laser controller is connected to the infrared pulse laser; and the ultrasonic probe is connected to the data collector.

5. The detection method of the multi-modal defect non-destructive detection device for metal rolling elements according to any one of claims 1 to 4, specifically comprising the following steps: Step 1: Based on the first detection optical path and the second detection optical path, optical detection is performed on the surface of the metal rolling body to obtain optical signals of the cylindrical surface and the end surface of the metal rolling body, and defects of the cylindrical surface and the end surface of the metal rolling body are determined according to the obtained optical signals; Step 2: Based on the third detection optical path, photoacoustic detection is performed on the shallow surface of the metal rolling element to obtain a photoacoustic signal of the shallow surface of the metal rolling element, and a defect of the shallow surface of the metal rolling element is determined according to the obtained photoacoustic signal; Step 3: Based on the third detection optical path, ultrasonic detection is performed on the inside of the metal rolling element to obtain an ultrasonic signal inside the metal rolling element, and internal defects of the metal rolling element are determined based on the obtained ultrasonic signal; Step 4: Based on the surface defects, shallow surface defects and internal defects of the metal rolling element, multi-modal signal fusion is performed to obtain fused defect information, and the defects are located based on the fused defect information.

6. The detection method of the multi-modal defect non-destructive detection device of a metal rolling element according to claim 5, characterized in that: The acquisition process of the optical signal on the surface of the metal rolling body cylinder is that the linear array camera collects the optical signal reflected from the surface of the metal rolling body cylinder line by line, and the formula of the collected optical signal is: I optical,line =∫ y I(x',y')d: Among them, I optical,line is the optical signal collected by the line array camera, x' and y' are the pixel coordinates collected by the line array camera, and x and y are the coordinates of the metal rolling body in the actual physical space; I(x', y') is determined by the surface reflectivity R(x, y) and the light source intensity I0, and the formula is as follows: I(x',y')=I0R(x,y); The process of determining the surface defects of the metal rolling element cylinder is to use the optical signal I optical,line Determine the surface texture and defect characteristics of metal rolling elements, and obtain the morphological characteristics of protrusions, cracks or scratches on the surface of metal rolling element cylinders through three-dimensional reconstruction; The formula for the three-dimensional reconstruction is as follows: Where z(x,y) is the surface height distribution, d is the projection grating spacing, and I1, I2, I3, and I4 are the light intensity values ​​after fringe phase shift.

7. The detection method of the multi-modal defect non-destructive detection device of a metal rolling element according to claim 5, characterized in that: The process of acquiring the optical signal of the end surface of the metal rolling element is as follows: Calculate the reflected light intensity I(x,y) on the end surface of the metal rolling element using the following formula: I(x,y)=I0R(x,y)=I0cos n (θ); Where I0 is the intensity of the light source, x and y are the coordinates of the metal rolling body in the actual physical space, R(x,y) is the reflectivity, θ is the angle between the normal line of the end surface of the metal rolling body and the direction of the annular light source, and n is the reflection distribution index; Then the area array camera records the two-dimensional light intensity distribution of the reflected light intensity on the end surface of the metal rolling element to obtain the optical signal. The calculation formula is as follows: I optica,lring =I (i,j) =∫ Δx ∫ Δy I(x,y)dxdy; In the formula, I optical,ring is the optical signal collected by the area array camera, Δx is the spatial resolution, Δy is the sampling interval, and the light intensity corresponding to the pixel (i, j) is determined by the reflection characteristics of the end surface of the metal rolling element; The process of determining the surface defects of the metal rolling element end is to use the discontinuity of light intensity distribution to detect surface pits, scratches or coating shedding, and analyze the image gradient information after optical distortion correction to extract subtle defects.

8. The detection method of the multi-modal defect non-destructive detection device of a metal rolling element according to claim 5, characterized in that: The process of acquiring the photoacoustic signal of the shallow surface layer of the metal rolling element is as follows: The energy absorbed by the metal rolling element is converted into heat energy, which causes transient expansion. The sound pressure caused by the thermal expansion satisfies the sound wave equation: In the formula, p represents the sound pressure, v represents the speed of sound wave propagation, and t represents time; The time harmonic solution of the sound pressure is: p(x,t)=P0exp[j(ωt-kx)]; Where p(x,t) represents the time harmonic of the sound pressure, P0 represents the sound pressure amplitude, and k is the wave number. The calculation formula is: The calculation formula of P0 is: P0=P acoustic =βA e ; Where P acoustic is the sound pressure amplitude of the photoacoustic signal, β is the conversion coefficient of the photoacoustic effect, which depends on the thermal expansion coefficient, thermoelastic properties and sound wave propagation efficiency of the material, A e is the energy absorbed by the metal rolling element, and the calculation formula is as follows: A e =I0f(x,y,z)g(t)α; Where f(x,y,z) is the spatial distribution of laser energy, g(t) is the time distribution function, usually an exponential pulse, and α is the material absorption coefficient; Then, the photoacoustic signal is obtained through the sound pressure formula generated by the photoacoustic effect. The formula is as follows: I photoacoustic =P acoustic ; In the formula, I photocoustic It is a photoacoustic signal; The process of determining the shallow surface defects of the metal rolling element is to reveal the type and size of the defect through the frequency characteristics of the photoacoustic signal, and then calculate the defect depth through the ultrasonic delay. The formula is as follows:

9. The detection method of the multi-modal defect non-destructive detection device of a metal rolling element according to claim 5, characterized in that: The process of acquiring the ultrasonic signal inside the metal rolling element is as follows: Ultrasonic waves satisfy the wave equation: In the formula, u is displacement, v represents propagation velocity, and t represents time; The ultrasonic signal is obtained through the ultrasonic probe echo signal: I ultrasound =A echo ; In the formula, I ultrasound is the ultrasonic signal, A echo is the amplitude of the ultrasound probe echo signal; The calculation formula of the echo signal V(t) received by the ultrasonic probe is as follows: V(t)=G∫ 孔径 p(x,y,t)dxdy; Where G is the sound wave transfer function, which represents the loss and scattering effect of sound waves propagating inside the metal rolling element, p(x, y, t) is the distribution of sound pressure, and x and y represent the spatial coordinates of the metal rolling element; The amplitude A of the ultrasonic probe echo signal echo Corresponding to the maximum value of V(t); The process of determining the internal defects of the metal rolling element is to use the amplitude A of the echo signal of the ultrasonic probe echo Determine the characteristics of the defect and calculate the defect depth by ultrasonic delay. The formula is as follows: Where d is the defect depth, v is the propagation velocity of the sound wave, and Δt is the time difference of signal propagation.

10. The detection method of the multi-modal defect non-destructive detection device of a metal rolling element according to claim 5, characterized in that: In step 4, the multimodal signal fusion is achieved by weighted summation: I fused =w1I optical,line +w2I optical,ring +w3I photocoustic +w4I ultrasound ; Among them, I fused is a multimodal fusion signal, and the weights w1, w2, w3, and w4 are determined by signal-to-noise ratio optimization. The calculation formula is as follows: In the formula, w i represents the weight of the i-th signal, SNR i represents the signal-to-noise ratio of the ith signal, P signal,i Represents the signal power, P noise,i represents the noise power; The calculation formula for defect location is as follows: Where d is the defect depth, v is the propagation velocity of the sound wave, and Δt is the time difference of signal propagation.

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